1. Field of the Invention
The present invention relates to a laser distance measuring apparatus, and more particularly, to a laser distance measuring apparatus utilizing a liquid display module for distance measurement.
2. Description of the Related Art
A laser scale is used to set a shutter device for maintaining phase difference accuracy between a measuring light and the reference light for laser distance measuring. For example, U.S. Pat. No. 7,471,377B2 discloses a measuring system which comprises a shutter device for shielding interference generated during measuring light emitted is set in a light path passed by the reference light. Additionally, the shutter device is utilized to shield undesired light which is the measuring light reflected to the path of the reference light, to avoid interference of the undesired light received by a receiver from decreasing accuracy of a measured result. However, utilizing the shutter device consumes more power because the shutter device needs a certain amount of current for actuation. Moreover, the shutter device generates vibration and noise during operation. In addition, when a target is a substance with high reflectivity or within a short distance, intensity of measured signal reflected from the target will be very large to over an acceptable range, thus es a saturated electronic signal will be outputted from receiver, and thereby making the laser scale unable to calculate a distance by the electronic signal.